This isn't always an option any more. Everyone wants to bring their stuff onboard because of the horrors of checked baggage, so good luck having room in the overhead compartments if you're boarding zone 5. The article mentions "Royle says she was asked by an Air Canada representative to check her carry-on suitcase for her flight from Toronto to Newfoundland in March", so yeah Air Canada lost her carry on bag. I've witnessed pretty violating experiences with Air Canada with people trying to pack light and then getting stripped of their belongs "because there's no room in the cabin". At the end of the day you have to comply with airline employees.